Embodiments of the invention relate to a sensor system for detecting and specifying individual particles in a fluid.
In many applications, it is desirable to be able to detect microorganisms in an inexpensive and rapid manner, for example in the field of water supply. A widespread method is to let microorganisms grow on a culture medium for their detection. This as a rule lasts for 24 to 48 hours, so that the detection lasts quite some time. It is particularly with respect to a water supply, for example in the foodstuffs industry, that it is desirable to be able to detect bacteria as soon as possible, in order to be able to stop the production, as the case may be.
In the last years other methods have been developed, in order to be able to ascertain and quantify bacteria, which function in a quicker manner. Thereby however, the problem arises that the very simple functioning methods often require a very large number of bacteria, whilst methods which may detect a very low number of bacteria are very expensive.
U.S. Pat. No. 5,811,251 discloses a system, with which the number of living microorganisms is counted based on a CCD system. U.S. Pat. No. 5,972,641 and U.S. Pat. No. 5,518,894 disclose quick-test systems based on statistical methods, in order to determine the number of bacteria present. These methods also require up to eleven hours in order to ascertain a low number of bacteria.
Moreover, methods for detecting microorganisms based on fluorescence and laser light are known, for example, from U.S. Pat. No. 5,891,394, U.S. Pat. No. 5,858,697, U.S. Pat. No. 5,763,203, U.S. Pat. No. 5,751,839 and U.S. Pat. No. 5,663,057. The disadvantage of these methods is that an expensive laser light source is required. Moreover, immune tests are also known, which are used for detecting certain types of microorganisms. However, the application of these tests is limited and it is necessary to manufacture antibodies for each microorganism to be detected, which is time consuming and costly.
It is therefore desirable to provide an inexpensive sensor system for detecting and specifying individual particles in a fluid.